Combo DVD burner drives (ones that read and burn both DVDs and CDs) have at least two if not three lasers and associated circuits. We have heard of cases where one laser or the circuits for it has malfunctioned after the drive has been used a while.
You could try the Plextor drive connected to another computer, or with different burning software, or flash it with updated or older firmware which rarely would have anything to do with such a problem unless it happened only after you flashed the firmware, but if that doesn't help and there's something physically wrong it's time to replace the drive, or the other drive, if you want to be able to burn DVDs.
You could try using a laser lens cleaning CD in it, but a dirty lens probably has nothing to do with your problem.
If you have more than one burning program installed other than the CD burning one built into XP, try un-installing all but one - sometimes they clash with each other, especially since they often have some modules that are running all the time, such as ones that detect if a burnable disk has been inserted.
Some systems software installations
- don't get along with Nero's InCD module
- don't get along with the Imagedrive feature of more recent Nero versions.
See this for more info:
- for either or both, you may need to un-install that if it can be un-installed separately in Add/Remove Programs, or un-install Nero then select a Custom installation and de-select installing it.
If the Plextor drive is IDE connected and capable of burning DVD +R or DVD -R disks at 16X or faster, it is capable of UDMA 66 and must be connected to an 80 wire data cable in order to be able to run at up to it's max speed. It may not be detected properly, and if it isn't the burning software may not work properly, if it is connected to a 40 wire data cable.
It is common to un-intentionally damage IDE data cables, especially while removing them - the 80 wire ones are more likely to be damaged. What usually happens is the cable is ripped at either edge and the wires there are either damaged or severed, often right at a connector or under it's cable clamp there, where it's hard to see - if a wire is severed but it's ends are touching, the connection is intermittant, rather than being reliable.
Another common thing is for the data cable to be separated from the connector contacts a bit after you have removed a cable - there should be no gap between the data cable and the connector - if there is press the cable against the connector to eliminate the gap.
80 wire data cables are also easily damaged at either edge if the cable is sharply creased at a fold in the cable.
Try another data cable if in doubt.
If you have re-loaded Windows from scratch since the last time the Plextor drive burned DVD disks properly, if you haven't already done so, you must load the drivers for at least the main chipset, otherwise your optical drive(s) may not be detected properly, and if it isn't the burning software may not work properly.
Whenever you load Windows from a regular Windows CD (or DVD) from scratch, after Setup is finished you must load the drivers for the mboard, particularly the main chipset drivers, in order for Windows to have the proper drivers for and information about your mboard hardware, including it's AGP or PCI-E, ACPI, and hard drive controller support. If you have a generic system and have the CD that came with the mboard, all the necessary drivers are on it. If you load drivers from the web, brand name system builders and mboard makers often DO NOT have the main chipset drivers listed in the downloads for your model - in that case you must go to the maker of the main chipset's web site, get the drivers, and load them.